An acrylonitrile-butadiene-styrene (ABS) resin obtained by polymerizing a diene-based rubbery polymer, an aromatic vinyl-based monomer, vinyl cyanide-based monomer and so on is excellent in impact resistance, moldability, outer appearance and the like, and is widely used in various applications such as office automation equipment, home electric appliances and miscellaneous goods. However, since the ABS resin has many chemically unstable double bonds in the main chain of the polymer, it is easily degraded by ultraviolet rays and the like, and is poor in weather resistance, and therefore difficult to use outdoors. Accordingly, a method using a saturated rubbery polymer having no double bond in the main chain has been proposed, and as a typical example thereof, an acrylonitrile-styrene-acrylate (ASA) resin produced using an acryl-based rubbery polymer is known. While the acryl-based rubbery polymer which is a saturated rubber is stable to ultraviolet rays, and thus has excellent weather resistance, it has the problem that its impact resistance is lower as compared to that of the ABS resin.
In this connection, as a thermoplastic resin composition excellent in impact resistance, rigidity and outer appearance, for example, there has been proposed a thermoplastic resin composition containing an acrylic rubber-based graft copolymer obtained by graft-polymerizing a vinyl-based monomer in the presence of a rubbery polymer including acrylic acid ester-based monomer units and polyfunctional monomer units, wherein the total amount of the polyfunctional monomer units in the rubbery polymer is 0.3 to 3 parts by mass based on 100 parts by mass of the acrylic acid ester-based monomer units, and the graft copolymer includes 30 to 95% by mass of polyfunctional monomer units having two unsaturated bonds and 5 to 70% by mass of polyfunctional monomer units having three unsaturated bonds in 100% by mass of the total of the polyfunctional monomer units (see, for example, Patent Document 1).
As a method for producing a thermoplastic resin excellent in impact resistance, and outer appearance such as glossiness and color development, for example, there has been proposed a method for producing an impact-resistant thermoplastic resin in which 10 to 95 parts by weight of a monomer including a polyfunctional monomer is blended and polymerized in the presence of 5 to 90 parts by weight of a graft polymer rubber (A) obtained by emulsification-polymerizing 60 to 95 parts by weight of a polymerizable monomer (a) containing an acrylic acid ester having an alkyl group with a carbon number of 1 to 13 in the presence of 5 to 40 parts by weight of a diene-based polymer (b) (see, for example, Patent Document 2).
As a thermoplastic resin composition excellent in color development, weather resistance, impact resistance and processability, for example, there has been proposed a thermoplastic resin composition including 10 to 80 parts by weight of a graft copolymer obtained by graft-polymerizing a vinyl-based monomer with an acrylic acid ester-based rubber polymer, and 20 to 90 parts by weight of a styrene-based copolymer, the acrylic acid ester rubber polymer being a rubber polymer produced by a particle expansion method using an acid group-containing latex (see, for example, Patent Document 3).
As a thermoplastic resin composition which is excellent in impact resistance, fluidity and surface gloss and which is freed from bronzing phenomenon, for example, there has been proposed a thermoplastic resin composition which includes 10 to 100% by weight of a graft copolymer obtained by graft-polymerizing a vinyl-based monomer in the presence of an acryl-based rubber including 20 to 80% by weight of an acryl-based rubber of less than 0.2μ and 20 to 80% by weight of an acryl-based rubber of 0.2 to 0.6μ, and 0 to 90% by weight of a copolymer formed from a vinyl-based monomer (see, for example, Patent Document 4).
Generally, for using resin materials in home electric appliances and office automation equipment, flame retardancy may be required, and since most of resin compositions containing the ABS resin are flammable, various techniques for making the ABS resin flame-retardant have been devised. As a method for making an ABS resin composition flame-retardant, a method is most widely employed in which an organic halogen compound having high frame retardation efficiency is blended in a resin to make the ABS resin composition flame-retardant. However, there is the problem that weather resistance is outstandingly reduced when flame retardancy is imparted to the ABS resin using an organic halogen compound. In this connection, there has been a flame-retardant thermoplastic resin composition including an organic halogen compound and a yellow pigment has been proposed (see, for example, Patent Document 5).